It's the first time that Nielsen has compiled e-books, with Amazon.com, Barnes & Noble, Apple and Google among those participating. BookScan numbers reflect around 75 percent of hardcover and paperback sales and offer a rare look at raw data from an industry known for being secretive about how much books actually sell. But the Nielsen statistics became increasingly limited as e-sales took off.

"These new charts uniquely reflect what people are really buying and reading and will most definitely advance the industry's understanding of e-book best sellers."